PDF signature validation fails when signed with ECDSA-SHA256

[Alejandro]

Hello!

A PDF file that was successfully signed using the PdfSignature class cannot be validates afterwards.

The digital ID used to sign the PDF is a self-signed one, created with the elliptic curve encryption algorithm and SHA-256 as the digest algorithm.

The simplified code I'm using for validation is:

var doc = new PdfLoadedDocument(filename);
var sf = form.Fields[0] as PdfLoadedSignatureField;
var result = sf.ValidateSignature();

The 'result' variable after the validation contains:

The collection 'SignatureValidationErrors' contains one item with the text "The document has been altered or corrupted since the signature was applied".

As a side note, the file was not modified after being signed; also when opening the PDF in Adobe the signature is validated without problems.

I'm attaching a sample PDF file for you to check.

Can you please confirm if this is a bug with ECDSA-sha256 signed files? I'm using SF version 20.1.0.56

Thank you

Alex

Attachment: 20205934740_84174fda.zip

[Gowthamraj Kumar]

Hi Alejandro,

We were able to reproduce the reported issue with provided details on our end. Currently, we are validating on this and we will update the further details on May 25^th 2022.

Regards,

Gowthamraj K

[Gowthamraj Kumar]

Hi Alejandro,

We confirmed the issue “PDF signature validation fails when verifying digitally signed with the ECDSA-SHA256 algorithm” as a defect in our product. Since you are using a weekly NuGet release version, we will include the fix for this issue in our weekly NuGet release, which will be available on June 7^th, 2022.

Please use the below feedback link to track the status of the reported bug.

https://www.syncfusion.com/feedback/35187/pdf-signature-validation-fails-when-verifying-digitally-signed-with-the-ecdsa

Note: If you require patch for the reported issue in any of our Essential Studio Main or SP release version, then kindly let us know the version, so that we can provide a patch in that version based on our SLA policy.

Please let us know if you need any further assistance in this.

Regards,

Gowthamraj K

[Alejandro]

Hello Gowthamraj,

Thank you for your feedback on the reported issue.

I'll be waiting for the weekly nuget release on june 7th.

Regards,

Alex

[Gowthamraj Kumar]

Hi Alejandro,

We have included the fix for the reported issue “PDF signature validation fails when verifying digitally signed with the ECDSA-SHA256 algorithm” in our latest weekly NuGet release (v20.1.0.59). Please use the below link to download our latest weekly NuGet,     

https://www.nuget.org/packages/Syncfusion.Pdf.AspNet.Mvc5/20.1.0.59   

Please let us know if you have any concerns about this 

Regards,

Gowthamraj K

[Alejandro]

Hello Gowthamraj,

I made a test with the weekly release 20.1.0.59 and the validation of document signed with ECDSA was successful.

Thank you for your support

Regards

Alex

[Gowthamraj Kumar]

Hi Alejandro,

Thank you for your update. We are glad to know that the reported issue is resolved.

Please let us know if you need any further assistance in this.

Regards,

Gowthamraj K